Check here - http://linhes.org/ BTW they run Arch. Source: about 2 years ago

You are correct, fire tv os is based on android os but not android tv os. https://developer.amazon.com/docs/fire-tv/fire-os-overview.html. Source: almost 2 years ago

A push notification is a note which pops up on a mobile device. App publishers can send them, and at the same time, users do not have to run the app or to use their devices to receive them. They can do many things; for instance, they can show the latest sports scores as well as get a user to take action. They can also let you download a coupon, or let a user know about an event, such as a flash sale. Push... Source: about 2 years ago

Https://developer.amazon.com/docs/fire-tv/fire-os-overview.html helps. Source: over 2 years ago

The model name should be listed under "Device name". This works by looking up the model number from information taken from Amazon's list of Fire TV devices (here). (This is updated automatically, and should also work with Fire tablets/TVs, other Android devices etc.. Silk or other Chromium-based browsers should work, however Firefox doesn't supply this device information.). Source: over 2 years ago

Amazon has a list here. I got a Toshiba TV from the Prime Day sale myself for my bedroom. It looks like newer 4k fire TVs are getting Fire OS 7, but the HD versions aren't. On the stick side, the Fire TV Stick and Stick Lite have Fire OS 7, but not the aging 4k that they still actively sell as their only 4k option. It came out in 2018 and is overdue for a refresh. Source: about 3 years ago